Casey Affleck: Joaquin Phoenix Documentary 'I'm Still Here' Was Fake

Casey Affleck has admitted that 'I'm Still Here,' his documentary that chronicles Joaquin Phoenix's two-year descent into madness as an aspiring rapper, was a stunt.

"It's a terrific performance, it's the performance of his career," he told the New York Times.

An excerpt from the interview:

Virtually none of it was real. Not even the opening shots, supposedly of Mr. Phoenix and his siblings swimming in a water hole in Panama. That, Mr. Affleck said, was actually shot in Hawaii with actors, then run back and forth on top of an old videocassette recording of "Paris, Texas" to degrade the images.

"I never intended to trick anybody," said Mr. Affleck, an intense 35-year-old who spoke over a meat-free, cheese-free vegetable sandwich on Thursday. "The idea of a quote, hoax, unquote, never entered my mind."

Still, he acknowledged that Mr. Letterman was not in on the joke when Mr. Phoenix, on Feb. 11, 2009, seemed to implode his own career by showing up in character as a mumbling, aimless star gone wrong.

Watch Joaquin's bizarre Letterman appearance here. He is booked to return to the 'Late Show' September 22.